The invention relates to printing composite images that can contain large amounts of information, optionally including redundant information, in an eye-pleasing format. The composite images provide high information density, with redundancy, in a highly reliable and visually pleasing format. The composite images are achieved with a novel arrangement of largely invisible, machine-readable postage evidencing information, e.g., Information Based Indicia (IBI) images containing 2-D bar code information, and dark, visible images containing human-readable postage information, which typically includes address information. The images can be printed using conventional ink jet printers.
Postage evidencing information, including IBI images, is a significant feature of the Information-Based Indicia Program (IBIP) implemented by the United States Postal Service (USPS) as a distributed trusted system. The IBIP includes open IBI postage evidencing systems, which can apply postage in addition to performing other functions not possible with conventional postage machines. The IBIP requires printing high density, two-dimensional (2-D) bar codes, such as PDF417 bar codes, on mailpieces. The requirements for printing a PDF417 2-D bar code are set forth in The Uniform Symbology Specification. The Postal Service expects the IBIP to provide cost-effective assurance of postage payment for each mailpiece processed. IBI images comprise certain human readable information and two-dimensional (2-D) bar code information, which can contain such assurance. However, printed information is often obscured, diminishing its reliability even with error correction technology. There is a need for a high-density image format that includes both human readable and bar code information with high reliability.
The USPS has published specifications for the IBIP such as PERFORMANCE CRITERIA FOR INFORMATION-BASED INDICIA AND SECURITY ARCHITECTURE FOR OPEN IBI POSTAGE EVIDENCING SYSTEMS (PCIBI-O), dated Jan. 12, 1999; PERFORMANCE CRITERIA FOR INFORMATION-BASED INDICIA AND SECURITY ARCHITECTURE FOR CLOSED IBI POSTAGE METERING SYSTEMS (PCIBI-C), dated Feb. 23, 2000; and PERFORMANCE CRITERIA FOR INFORMATION-BASED INDICIA PROGRAM (IBIP) SYSTEMS EMPLOYING CENTRALIZED POSTAL SECURITY DEVICES, dated Aug. 17, 2000; (collectively referred to herein as the “IBIP Specifications”). The IBIP includes interfacing user (customer), postal and vendor infrastructures, which are the system elements of the program. The term “postage evidencing information” is meant to include IBI images meeting the current IBIP Specifications as well as alternative formats. The IBIP Specifications require a minimum bar code read rate of 99.5% and place the responsibility on each IBIP vendor to meet this requirement.
A user infrastructure, which typically resides at the user's site, can comprise a postage security device (PSD) coupled to a host system. The PSD is a secure processor-based accounting device that dispenses and accounts for postal value stored therein. The host system (Host) may be a personal computer (PC) or a meter-based host processor. Alternatively, the PSD can be located on a server remote from the user. Wherever the PSD is located, it would be desirable for IBIP indicium to be printed using an open system comprised of conventional desk-top and other ink jet printers not dedicated to postage, but this capability has not been fully realized without sacrificing readability or the visual appearance of the printed mailpiece.
The IBIP Specifications permit large format IBI images, e.g., 2-D bar codes, but there are several practical limits to the use of images that overlap conventional address information. For example, black and other dark colored inks tend to quench the fluorescence from invisible inks. Thus, if conventional address information overlaps with the IBI image, the IBI image could lose reliability and fall outside of the Specifications. Also, simple smudging of an envelope can have the same effect. The provision of error correction technology can provide a margin of protection but as conventionally employed, due to its mathematical underpinnings, must operate from a limited data set. It would be desirable to provide a technology that supplemented and, preferably, enhanced error correction technology.
The need for high resolution has posed significant technical challenges. Current systems are challenged to provide a suitable combination of convenience, acceptable appearance and high readability at high information densities. In U.S. patent application Ser. No. 10/413,096, filed concurrently herewith, which is incorporated herein by reference in its entirety, there is described a system which enables printing large amounts of information on a mailpiece without causing the mailpiece to become unsightly due to the presence of too much printing in a small space. The system employs luminescent invisible or lightly colored ink for printing at least a portion of the bar code portions of the information. This system has an advantage that attempts to maximize print information in an invisible 2-D bar code will not affect the human readable portion; but, unless provision is made for redundancy for the 2-D bar code information, problems can still occur.
When using invisible, fluorescent ink for printing the 2-D bar code, the bar code will not obscure the human readable printed information, but the human readable printed information can obscure the bar code. Overlap of the 2-D bar code and the printed conventional human readable address information can diminish the readability of the 2-D bar code or other information to the extent that even error correction codes cannot obtain the required read rates. Typically, suitable fluorescent inks irradiate in the red or infrared range when excited by ultraviolet light. But, because black and other dark visible inks tend to quench fluorescence, any overprinting of dark ink on a fluorescent ink can cause obscuration to the point of diminishing or destroying readability.
There remains a need for a method that provides machine-readable IBI images containing both large format 2-D bar code information with high levels of error correction in invisible or light colored luminescent ink, along with conventionally printed address and postage information to provide increased read rates and the provision of high information density without obscuring any one component. It would be desirable in this context to provide especially enhanced readability with a high contrast of the fluorescent image in a format that enabled improved read rates in the presence of obscured information.